\class{Packer} instances have the following methods:

Returns the current pack buffer as a string.

Resets the pack buffer to the empty string.

In general, you can pack any of the most common XDR data types by

calling the appropriate \code{pack_\var{type}()} method. Each method

\method{pack_int()}, \method{pack_enum()}, \method{pack_bool()},

\method{pack_uhyper()}, and \method{pack_hyper()}.

Packs the single-precision floating point number \var{value}.

Packs the double-precision floating point number \var{value}.

The following methods support packing strings, bytes, and opaque data:

Packs a fixed length string, \var{s}. \var{n} is the length of the

string but it is \emph{not} packed into the data buffer. The string

is padded with null bytes if necessary to guaranteed 4 byte alignment.

Packs a fixed length opaque data stream, similarly to

\method{pack_fstring()}.

Packs a variable length string, \var{s}. The length of the string is

first packed as an unsigned integer, then the string data is packed

with \method{pack_fstring()}.

Packs a variable length opaque data string, similarly to

\method{pack_string()}.

Packs a variable length byte stream, similarly to \method{pack_string()}.

The following methods support packing arrays and lists:

Packs a \var{list} of homogeneous items. This method is useful for

lists with an indeterminate size; i.e. the size is not available until

the entire list has been walked. For each item in the list, an

unsigned integer \code{1} is packed first, followed by the data value

from the list. \var{pack_item} is the function that is called to pack

the individual item. At the end of the list, an unsigned integer

\code{0} is packed.

Packs a fixed length list (\var{array}) of homogeneous items. \var{n}

is the length of the list; it is \emph{not} packed into the buffer,

but a \exception{ValueError} exception is raised if

\code{len(\var{array})} is not equal to \var{n}. As above,

\var{pack_item} is the function used to pack each element.

Packs a variable length \var{list} of homogeneous items. First, the

length of the list is packed as an unsigned integer, then each element

is packed as in \method{pack_farray()} above.

\subsection{Unpacker Objects}

\label{xdr-unpacker-objects}

The \class{Unpacker} class offers the following methods:

Resets the string buffer with the given \var{data}.

Returns the current unpack position in the data buffer.

Sets the data buffer unpack position to \var{position}. You should be

careful about using \method{get_position()} and \method{set_position()}.

Returns the current unpack data buffer as a string.

Indicates unpack completion. Raises an \exception{Error} exception

if all of the data has not been unpacked.

In addition, every data type that can be packed with a \class{Packer},

can be unpacked with an \class{Unpacker}. Unpacking methods are of the

form \code{unpack_\var{type}()}, and take no arguments. They return the

unpacked object.

Unpacks a single-precision floating point number.

Unpacks a double-precision floating point number, similarly to

\method{unpack_float()}.

In addition, the following methods unpack strings, bytes, and opaque

data:

Unpacks and returns a fixed length string. \var{n} is the number of

characters expected. Padding with null bytes to guaranteed 4 byte

alignment is assumed.

Unpacks and returns a fixed length opaque data stream, similarly to

\method{unpack_fstring()}.

Unpacks and returns a variable length string. The length of the

string is first unpacked as an unsigned integer, then the string data

is unpacked with \method{unpack_fstring()}.

Unpacks and returns a variable length opaque data string, similarly to

\method{unpack_string()}.

Unpacks and returns a variable length byte stream, similarly to

\method{unpack_string()}.

The following methods support unpacking arrays and lists:

Unpacks and returns a list of homogeneous items. The list is unpacked

one element at a time

by first unpacking an unsigned integer flag. If the flag is \code{1},

then the item is unpacked and appended to the list. A flag of

\code{0} indicates the end of the list. \var{unpack_item} is the

function that is called to unpack the items.

Unpacks and returns (as a list) a fixed length array of homogeneous

items. \var{n} is number of list elements to expect in the buffer.

As above, \var{unpack_item} is the function used to unpack each element.

Unpacks and returns a variable length \var{list} of homogeneous items.

First, the length of the list is unpacked as an unsigned integer, then

each element is unpacked as in \method{unpack_farray()} above.

\subsection{Exceptions}

\nodename{Exceptions in xdrlib module}